Various systems for finding a file, which has the possibility of a leakage of information, and obviating the information leakage have been proposed (for example, refer to patent document 1 and non-patent document 1). FIG. 53 is an explanatory diagram illustrating a patent document 1. As shown in FIG. 53, the system, which includes a file location detector, file attribute setting means, a file location comparator, and a program executioner, operates as follows. The file attribute setting means sets the location allowed as a file existence location. Next, the file location detector detects the location where the file exists. The file location comparator compares the file existence location set by the file attribute setting means with the file existence location detected by the file location detector. If a file exists outside the location set by the file attribute setting means, the file is decided as an information leaked file. The program executioner deletes or encrypts the file. Thus, such an operation allows a file having the possibility of information leakage to be found, thus preventing the information from being leaked.
In the operation disclosed in the non-patent document 1, a character string included in an information leakage prevented file is registered as a keyword. Next, a distributed file is analyzed to extract a character string included in the file. It is decided whether or not the extracted character string is included in the registered character string group. When the character string extracted from the file is in a registered state, it is decided that the file has the possibility of information leakage. Thus, interruption of the distribution of the file is instructed. Such an operation can decide the possibility of information leakage from the file to prevent a leakage of information.
[Patent Document 1]
Japanese Patent laid-open publication No. 2003-36208 (refer to pages 5-10 and FIG. 1)
[Non-Patent Document 1]
“eTrust Secure Content Manager r1.1”, [online], September, 2004, Computer Associates Co. Ltd., [retrieval on Nov. 25, 2004], Internet <URL:http://www.caj.co.jp/etrust/scm/pdf/pd.pdf>